The invention relates to a method for controlled braking of a door in the event of a breakdown, that is, in case of a failure of a mechanical component, with the help of the electromotive drive unit of the door.
With electronically powered doors customary today, such as rolling doors, overhead doors, sectional doors, or swinging doors, the door's mechanics are frequently arranged in such a way that the electromotive drive unit of the door is not required to power the full weight of the door. For this purpose the doors, depending on their construction and design, are equipped with various devices such as spring elements, cables, and counterweights, which ensure what only a part of the energy required for motion needs to be directed by means of the electromotive drive, and which can be summarized under the general category of balancing devices.
As soon as a balancing device of this type breaks down, for instance because a spring breaks or a rope connected with the counterweight tears, the result can be an undesired, uncontrolled, and dangerous downward motion, the so-called collapse, of a door.
Doors known in the art, the construction and power unit are designed in such a way that a balancing device can be dispensed with. With these doors, an additional electromechanical braking device frequently ensures that the door is held in the resting position after the power is switched off. With a malfunctioning of the braking device, for instance through eroded brake pads, with these doors as well the result can be a crash of the door.
Combinations of balancing device and electromechanical braking devices are also known in the art. Here the electromechanical braking device, for instance, has the task of rapidly bringing to a standstill a door that is in motion, for instance in case a holding point is reached, and of holding the door securely in this position until such time as another drive command is executed.
In the case of a defect in the braking device, a door in some cases cannot reach the desired holding position or the holding position is not held as long as desired, but instead the door slowly and unintentionally starts to leave the position.
To prevent a collapse of the door, various mechanical solutions are known in the art, such as those described in DE 37 01 251 C2, DE 38 14 275 C2, DE 41 38 711 C2, or DE 198 55 697 C2, and in which, for instance by means of pre-tensioned springs or centrifugally activated mechanical devices, additional braking devices are triggered or actuated, which more or less brake the door, for instance in the lateral tracks of the door, or which act mechanically on the door shaft in order to stop the uncontrolled motion of the door.
All technological solutions known in the art for preventing a door collapse for emergency braking have the disadvantage that additional mechanical devices are required whose functionality in most cases can only be tested with great difficulty during a normal life cycle of a door, and in which, in case of an intentional or unintentional triggering, can only be recognized with difficulty, the reason of the triggering of the device. With a few devices known in the art, in addition, it is impossible to recognize that they are in the triggered state, so that the user of the door facility can recognize the supposed cause of failure only after extensive searching.
The electrical power units for doors in common use today, the so-called door drivers, consist as a rule of an electric motor, which most often takes the form of a reasonably priced asynchronous AC induction motor, and which in most cases is directly connected with a flange-mounted gearbox, whereas the gearbox often takes the form of a so-called worm gear.
It is also customary in the art to feed door drive motors by a frequency converter, so that the door can be operated with different speeds and in order to maintain the possibility for gentle actuation and stopping of the door.
The frequency converter in this case, according to the state of the art, is a component of a complex door controller, which, besides comprising the frequency converter, also has at least one device with which the position of the door can be continuously ascertained. In patents DE 295 13 962 U1 and DE 101 42 431 B4, door controllers of this type, with integrated frequency converter and connected position sensors, are described.
Also reported in the art (DE 196 45 811 C2) is a control device for emergency switch-off. This control device from the art comprises a lifting tool. In lift operation this is intended to avoid any excess load on the lift machinery in the event of a breakdown, for instance from the load being caught. For this purpose any exceeding of a boundary value in the lift process is captured. This device from the art has the disadvantage that an additional capturing device for the mechanical excess load must be provided; for instance, a cable tension sensor is provided in the form of a load cell.
The technical problem that underlies the invention consists in providing a method by which the collapse of a door can be prevented without requiring additional devices on the door or the door driver that can be produced therefore with the devices door driver, door controller, frequency converter, and position sensor that are already available in the art. In addition the invention aims to provide a method that can, at least temporarily, assume the functioning for a defective electrical braking device of the door, and that reliably allows the signaling of a defective balance and/or braking device. In addition, a method is provided for applying the method.